This study is a modification of SPID 4230. The effects of the primary loading dose of 525 mg Clopidogres have been carefully studied. The dose was well tolerated and produced partial inhibition of platelet function within 2 hours of administration. This amendment proposes to now add a second loading dose of clopidogrel (525 mg) to be administered 12 hours after a primary loading dose (525 mg) to aspirin-treated coronary artery disease patients.